Treads of tires are required to have wet-grip performance, durability, abrasion resistance and other properties. Abrasion resistance is important especially for users in the North American market where the average monthly mileage is high. Thus, there is a need to improve abrasion resistance while maintaining wet-grip performance and durability, and even production cost.
In general, silica formulations have good wet-grip performance but are inferior in abrasion resistance to carbon black formulations. Possible ways to improve abrasion resistance are to increase the amount of silica and to use fine particle silica having excellent abrasion resistance or a silane coupling agent that strongly binds to polymers. These methods unfortunately increase the cost of the silane coupling agent. Therefore, it is desired to improve abrasion resistance by improving polymers or softeners.
Patent Literature 1 discloses a rubber composition for tire treads whose abrasion resistance, fuel economy, and wet-grip performance are improved by incorporating a liquid resin having a softening point of −20° C. to 45° C. and a specific silica.